Nanoparticles have unique properties (for example, optical, electromagnetic and catalytic properties, etc.) that are completely different from bulk properties. The reason why nanoparticles have such properties is because the nanoparticles have an increased specific surface area which results in a change in the properties. In metal nanoparticles, a localized surface plasmon resonance (LSPR) phenomenon is observed. The intensity or frequency of the absorption band of metal nanoparticles differs depending on the kind of metal nanoparticles and the kind of material on which nanoparticles are placed. Further, the surface plasmon frequency of metal nanoparticles differs depending on the size, shape and size distribution thereof.
Methods for preparing such nanoparticles can be divided into a top-down method and a bottom-up method. The top-down method is a process that sculpts a mass to make it small. This method has a limit to miniaturization, because it cannot prepare a material having a size of 50 nm or less. The bottom-up method is a process that prepares a new nanomaterial by combining atoms or molecules, like stacking bricks. Typical examples of the bottom-up method include self-assembly technology. Weak, reversible interactions such as hydrogen bonds, hydrophobic interactions and van der Waals forces act between biomolecules such as DNAs, RNAs and proteins. Such reversible interactions allow biomolecules to spontaneously undergo self-assembly into complex structures, and this phenomenon is called “self-assembly phenomenon”. In other words, nanostructures having a size of a few nanometers to a few tens of nanometers can be prepared by assembling biomolecules using this self-assembly phenomenon. However, because the self-assembly phenomenon spontaneously occurs under specific conditions, it is very difficult to delicately control the self-assembly process.
In an attempt to solve this problem, Korean Patent Laid-Open Publication No. 10-2012-0096120 discloses the use of a method of changing reaction conditions (i.e., temperature, pH or salt concentration) to control the self-assembly phenomenon. However, this method has a problem in that, because changes are applied to an aqueous solution of biomolecules, the biomolecules cannot be rapidly controlled.
Therefore, there is a need for continued studies on a method for preparing nanostructures having the same pattern, which can make a desired shape from the initial reaction stage.